Flanging propeller blank



Sept. 28 1937. -rm 2,094,076

FLANGING PROPELLER BLANK Filed July 5, 1933 Inuent'or: Erle Afwrfi'rv,

Patented Sept. 28, 1937 PATENT OFFICE,

FLANGING raornuna BLANK Eric Martin, Hartford, Conn., assignor to UnitedAircraft Corporation, East Hartford, 001111., a corporation of DelawareApplication July 5, 1933, Serial No. 579,137

8 Claims.

The invention relates to airplane propellers and particularly to theseparate blades thereof and has to do especially with the flange whichis usually provided for mounting such blades in propeller hubs.

While the present invention does not involve all the steps necessary tomake a propeller blade, it may be desirable to outline the proceedingsin manufacturing the propeller blade so that the relation of the presentinvention thereto may be clearly indicated.

A hollow metallic propeller blade may be made from a single tube ofsubstantially uniform diameter both internally and externally. One endof the tube is upset and made thicker. This may not only make that endof the tube larger in external but also smaller in internal diameter. Aportion of the thickened end of the tube is then turned outwardly tomake a circumferential flangeand the interior of the thickened end ofthe tube is dressed to enlarge it to substantially the same internaldiameter as the rest of the tube. The other end of the tube may then beswaged or otherwise tapered to a somewhat smaller diameter bothinternally and externally.

The blank may then be held by the flange while there is inserted into ita mandrel under sufficient pressure to bring the internal dimensions ofthe tube to approximately the size of the mandrel.

Thereafter the walls of the tube are brought to appropriate thicknessand the smaller end of the blank spun or otherwise closed. The preparedblank may then be deformedin dies to the desired final form of apropeller blade.

Purposes of the present invention include the provision of a propellerblade having a thickened shank portion provided with a securing flange;the provision of a novel method of forming a flange on the shank end ofthe propeller blade blank; the provision of a method of forming a flangeon the shank end of a propeller blade blank including first thickeningthe metal of such end and then gradually working the extremity of suchend outwardly whereby to'form a flange without distorting the flow linesof the metal from which the flange is formed; and the provision of amethod of forming a flange on the shank end of a propeller blade blankincluding first thickening the metal of such end by decreasing theinternal dimension and increasing the outside dimension and thengradually working the extremity of such end outwardly whereby to form aflange without distorting the flow lines of the metal from which theflange is formed.

In the accompanying drawing, which illustrates suitable embodiments ofthe invention, Figure 1. is a side elevation of a completed propellerblade of a type with which the present invention deals. 1

Fig. 2 is a transverse sectional view taken 5 through the body of thepropeller blade shown in Fig. 1 as on the line 2-2 of Fig. 1.

Fig. 3 is a side elevation, and Fig. 4 is an end elevation, of a tube ofthe type which preferably forms the initial piece of stock from whichthe 10 airplane propeller of the present invention is finally formed.

Figs. 5 to 13 inclusive are partially broken,

, partially sectioned, side elevations which illustrate successive stepsof operation upon one end 15 of the piece of stock shown in Figs 3 and 4during the formation of a flange thereon which, after subsequentoperations, will serve as means for supporting the propeller blade in ahub structure. 20

Fig. 14 is a side elevation of the piece of stock shown in Figs. 3 and 4after it has been subjected to the operation illustrated in Figs. 5 to13 inclusive whereby a flange is formed upon one end thereof, and afterit has been tapered and 5 reduced in diameter especially at the oppositeend to form a small end.

Referring now to Figs. 1 and 2 of the drawing, a propeller blade of thetype particularly adaptable to the practices of the present invention,is 3 shown. This propeller blade is of hollow construction, andpreferably formed of steel, and includes a main body portion 20 having atip 2| at one end thereof and a shank portion 22 at the opposite endthereof. with the broader aspects of the present invention, theparticular means provided in connection with the shank portion 22 foraiding in securing the propeller blade in a hub structure (not shown) ismore or less immaterial, a preferred form of 40 such means is shown inFig. 1 in the form of a single outwardly extending annular flange 23 atthe root end of the shank portion 22. It will also be understood thatthe main body portion 20 of the propeller blade is generally of airfoil45 section, and provided with a leading edge 24 and a trailing edge 25,and has a front or camber face 26 and a rear or flat face 21 and thatpreferably the main body portion 20 is more or less twisted or warpedover its length in order that 50 each increment of the length thereofhas substantially the same pitch as any other such increment.- Thehollow type of propeller blade is preferred generally for the reasonthat when properly constructed, it provides maximum 55 Although, inaccordance 35 strength for a. given weight. While all phases of theinvention are not confined thereto, the following description will dealsolely with the preferred form and manner of making the propeller bladeshown in Figs. 1 and 2. It may also be noted that although the propellerblade shown in Figs. 1 and 2 may be constructed of material other thansteel, the following description will deal solely with the constructionof such blade made from steel, and should it be desired to form such ablade from material other than steel, those skilled in the art willreadily recognize such variations or changes in the methods hereinafterdescribed as will be necessary in such cases.

In Figs. 3 and 4 is shown the piece of stock or blank 28 which forms thestarting point for the manufacture of the blade shown in Figs. 1 and 2.This piece of stock or blank 28 is a cylindrical steel tube of suitablelength and of an external andinternal diameter slightly larger andsmaller than the respective external and internal diameters of thefinished blade respectively at a point adjacent the outer end of theshank portion 22. Of course, in the broader aspects of the invention,the particular composition of the steel employed may vary in accordancewith the desire of the particular designer or manufacturer, but for thepurpose of illustration in the present case, will be considered to be ofthat type known as 4130-X, the composition of which is well known tothose in the industry and is disclosed, as for instance, in the S. A. E.Handbook published by Society of Automotive Engineers, Inc., 29 West39th Street, New York, New York.

Preferably, the first operations upon the blank 28 are in connectionwith the formation of the shank 22 and flange 23, as disclosed in Figs.5 to 13, inclusive. The first of these operations, as indicated in Fig.5, includes placing one end of the blank 28 in a die structure,indicated generally at 29. This die structure is provided with anopening 38 therein, which relatively closely embraces the circumferenceof the blank 28 at one end of the die structure and beyond such end ofthe die structure the opening is enlarged in diameter in concentricrelation with respect to the opening 38, as at 3|, this portion beingjoined to the opening 30 through a tapered shoulder portion 32. Inpositioning the blank 28 in the die structure 29, as illustrated in Fig.5, the left hand end of the blank 28 is preferably located slightlyinwardly or to the right from the left hand face of the die structure,and the blank 28 is suitably anchored against movement to the right, asindicated in .Fig. 5. As indicated in Fig. 5, there is employed a ram 33of a diameter to be freely received within the enlarged portion 3| ofthe opening in the die structure 29, and thereby to be guided therein.The ram 33 is provided with a pilot extension 34 of slightly smalleroutside diameter than the internal diameter of the blank and whichaccordingly provides a shoulder 35 at the junction of the ram and pilot34. The pilot 34 is entered into the bore of the blank 28 and the bodyof the ram 33 is entered into the opening 3| a sufiicient distance tobring the shoulder 35 into contact with the corresponding end of thestock 28 and sufficient pressure is exerted upon the ram 33 to cause thecorresponding end of the blank 28 to be upset and thereby cause it toconform externally to the Walls of the opening 3| and of the shoulder 32and internally to conform to the diameter of the pilot 34. Thisoperation forms an enlarged cylindrical portion 36 which eventually willprovide the flange 23 and an out- Wardly tapered portion 31 which whenbrought to completed form will provide part of the shank portion 22.This end of the blank has, of course, preferably previously been broughtto a forging temperature, approximately 2200 F. in the case of theparticular steel disclosed, for the purpose of subjecting it to thisstep of operation.

Upon completion of this operation, the blank 28 is removed from the diestructure, and the upset end thereof is again brought to forgingtemperature and .gain placed in a die structure similar to the diestructure 29, to be again acted upon by a ram similar to the ram 33. Inthis case, however, the opening in the die structure which correspondsto the opening 3| in Fig. 5 is of greater diameter than the opening 3|,while the opening in the die structure corresponding to the opening 30in Fig. 5 is the same as in Fig. 5, and accordingly the length of theshoulder in the die structure corresponding to the shoulder 32 in Fig.5, is correspondingly increased. The diameter of the ram in this case,corresponding to the ram 33 is of course increased in accordance withthe increase in diameter of the opening in which it is to be received,and the diameter of the pilot corresponding to the pilot 34 in Fig. 5 isslightly reducedover the diameter-of the pilot 34. With the modified diestructure and ram the upset end of the blank 28 is again acted upon insubstantiallythe same manner as described in connection with Fig. 5, theresult being substantially as indicated in Fig. 6, that is, the externaldiameter of the portion 36 is increased, and the internal diameter isdecreased over that indicated in Fig. 5, and the length of the taperedshoulder 31 is increased while the length of the end operated on issomewhat decreased.

The upset end of the blank 28 may be then again heated to forgingtemperature and may be again subjected to the action of apparatussimilar toth'at disclosed in Fig. 5 to further increase the diameter ofthe portion 36 and the length of the shoulder 31 and decrease theinternal diameter of the blank over the length of these portions so asto bring this end of the blank into substantially the form indicated inFig. 7. This end of the blank 28 is subjected to as many repetitions ofthis type of operation as is deemed necessary to bring this end of theblank into approximately the condition indicated in Fig. 8, havingproper regard to the grain structure and flow lines of the grain of themetal in such end. For this latter reason it will be apparent that,although the end of the blank as indicated in Fig. 3 could be brought tothe condition illustrated in Fig. 8 in a single operation instead of aplurality of operations as disclosed, the grain structure of the metalin such case might be adversely affected and the flow lines of the grainof the metal might be unduly distorted from the viewpoint of obtainingmaximum strength in this portion of the final product. By following outa suitable number of operations as described, it is possible to maintainsubstantially the same grain structure and grain flow lines as occur inthe original piece of stock or blank 28.

When the blank 28 reaches the form indicated in Fig. 8, the taperedshoulder portion 31 has assumed substantially the form and size of theshank portion 22 in the finished blade, its size of course beingslightly larger for the purpose of leaving suflicient stock thereon toclean it up in subsequent machining operations. The thickness of theportion 36 at this stage of operation is substantially greater than thethickness of the ing or belling the portion 36 flange 23 in the finalproduct. The internal diameter of the blank over the length of theportions 36 and 31, as indicated in Fig. 8, has been reducedsufliciently so that upon removing the excess metal from the interior ofthe blank at this point to bring it into conformance with'the diameterof the main body portion of the blank, any roughness or otherimperfections which may have appeared on the interior of the blank atthis "point during the upsetting operation will be fully removed.

It will be understood that the exact sizes or proportions indicated inthe drawing are not essential and that the deformation of the end of theblank 28 and at other points in the operation may be carriedout towhatever extent is desired or expedient to produce the desired propellerblade or blank.

The next steps of operation deal with the outward bending of the portion36 so as to form a blank, as indicated in Fig. 11 from which the flange23 may be formed. These steps of operation include preferably three ormore steps as indicated in Figs. 9, 10, and 11 in which the portion 36of the blank, as indicated in Fig. 8, is gradually bent outwardly withrespect to the axis of the blank until the metal of such portion isbrought into a plane perpendicular to the axis of the blank as indicatedin Fig. 11. These operations are preferably not of an upsettingcharacter but consist rather of an outwardly bendso as not to disturbthe grain structure or grain flow lines of thisportion and, of course,are preferably conducted While this portion of the blank is at aboutforging temperature. The operation may be performed in any suitablenumber of steps. The final step of operation in bringing this end of theblank to the formindicated in Fig. 11 may, if necessary, include acertain amount of forming, as distinguished from pure bending orbelling, in order to obtain the desired contour of this end. The entireprocedure may be effected by any suitable known means which are notshown.

The next operation, which is illustrated in Fig. 12, consists inmounting the blank 28 in a lathe or steady rest or other suitablestructure '(not shown) in which the blank may be accurately centered andby means of a tool such as 38 turning the periphery of the flangeportion 23 into a cylindrical form concentric with the axis of the blank28.

This end of the blank 28 is then accurately centered, as by means of asteady rest 39,'or in a lathe or other structure (not shown) and theexcess metal in the bore formed during the upsetting process disclosedin Figs. 5 to 8, inclusive, is then removed, as by means of a tool suchas 40 where the amount of metal to be removed is relatively large, or byother suitable means, so as to bring this portion of the bore intosubstantially accurate conformance with the initial bore of the blank,and then this portion is ground, buffed or otherwise acted upon to bringthe internal surface thereof into smooth, polished and unbroken relationwith respect to the main body portion thereof.

The blank having been provided with the flange as described may then betapered and considerably reduced in diameter at the other end M of theblank as shown in Fig. 14. This and the following steps in completingthe propeller blade form no part of the present invention and may beperformed in any suitable Way. They are referred to here merely toindicate one character of completed article for which the presentinvention may be suitable. The tapered blank may be brought to exactinternal dimensions by forcing into it a properly sized mandrel so as tocause the metal of the blank to set to the size of the mandrel. Theblank may be suitably treated to reduce its wall thickness if necessaryand the small open end may be closed by some such operation as spinning.The blank so prepared may be deformed as by dies to the preferred shapeand contour for an airplane propeller. Various other suitable orintermediate operations may be performed upon the blank when necessaryor desirable.

Variations in the operations and results indicated may be adopted oreffected when desired without departing from the present invention.

I claim as my invention:

1. In forming a radially outwardly extending flange on a tube, the stepsof upsetting an end of the tube to increase its external dimensions anddecrease its internal dimensions, belling a portion of said endand'outwardly bending the belled portion of said end to form the flange.

2. In the formation of a propeller blade blank from a hollow metal tube,the steps in the formation of the shank end of the blank includingupsetting one end of the tube to form an end portion of increased andsubstantially uniform wall thickness and an adjoining portion of varyingwall thickness, belling a portion of said end and outwardly bending atleast a portion of said belled end portion outwardly to form a flange.

3. In the formation of a propeller blade blank from a hollow metal tube,the steps in the formation of the shank end of the blank includingupsetting one end of the tube to form a cylindrical end portion of adifferent thickness and an adjoining portion of tapering formation,belling the cylindrical portion of said end and outwardly bending thebelled cylindrical portion to form a radially outwardly directed flange.

4. In the formation of a propeller blade blank from a hollow metal tube,the steps in the formation of the shank end of the blank includingupsetting one end of the tube to form an end portion of increased andsubstantially uniform wall thickness and an adjoining portion of vary--ing wall thickness by a series of axially upsetting operationseachconducted while the end is in heated condition, and outwardly bellingthe portion having a uniform wall thickness by a series of outwardlybending operations, each conducted while the end is in heated condition,to form an annular outwardly directed flange.

5. .In the formation of a propeller blade blank from a hollow metaltube, the steps in the formation of the shank end of the blank includingupsetting one end of the tube to form an end portion of increased outerand decreased inner dimensions, bending the extremity of the end portionoutwardly to form an outwardly directed flange, and removing metal fromthe interior surface of the end portion to bring its dimensions intosubstantial conformance with the original inner dimensions of the tube.

6. In the formation of a propeller blade blank from a hollow metal tube,the steps in the formation of the shank end of said blank includingupsetting one end of said tube to form an end portion of increased andsubstantially uniform wall thickness and an adjoining portion of varyingwall thickness, and outwardly bending a portion only of said end portionto form a flange.

'7. In the formation of a propeller blade blank tion of increased andsubstantially uniform wall thickness and an adjoining portion of varyingwall thickness by a series of axially upsetting operations eachconducted while said end is in heated condition, and then outwardlybelling said portion having a uniform wall thickness by a series ofoutwardly bending operations, each conducted while said end is in heatedcondition, to form an annular outwardly directed flange.

ERLE MARTIN.

